In the repair of automobile bodies it is sometimes necessary to apply a composition to a substrate in order to build up or fill in the substrate as, for example, to fill dents in the auto body being repaired. A rough shaping or forming is achieved while the composition is still plastic and formable and a final finish is usually achieved by sanding or filing. Such repair compositions are herein called "stopping compositions" or "auto repair stoppers". Unsaturated polyester resins as binders for stopping compositions, e.g. car repair stoppers, have been known for a long time. However, as a rule they require reactive solvents, such as styrene, as copolymerizable monomers.
One exception is the stopping compositions described in DE-OS 3 409 271, which are based on unsaturated polyesters which have such low viscosities that they can absorb the large quantities of filler characteristic of stopping compositions, and which can be hardened in the absence of copolymerizable monomers with the aid of peroxides to give non-tacky products. Hardening is in general effected at room temperature and resulting coatings which can easily be abraded but which are of a very low hardness are obtained after about 4 hours.
The object of the present invention is to provide a new process for the production of coatings using stopping compositions which, using monomer-free stopping compositions, leads within a short time to surfaces which are hard but can readily be abraded.